Unified tabular interface

[kdarras]

At the moment, we separate the dashboard (formerly "administrative interface") from the read-only front-end where people browse data and from which they open recordings.

Both interfaces can be merged into one, table-based interface with lateral tabs, which will display the proper functionalities depending on the user's permissions. However, these features should only be shown after the user clicks a "manage" button or similar, to toggle from a read-only to a write view.

This should be easier for the users, and also simpler for the web devs.

User-level data (multiple users for project managers, personal user data, and settings) should still be accessed from a separate page by clicking on the user name.

This should preserve the ability to display Leaflet maps, and the customisable view (i.e. letting users choose which columns to show) will enable users to define their own views and the ones of the users that they manage. It should be possible to add columns for spectrograms, with thumbnail of user-specified size, or waveforms, or power spectra.

Scatterplots / XY plots would replace timelines (#555). Tables would be customisable (#558).

Open questions to enhance the sustainability and simplicity of the web development work:

• How to sustainably and flexibly define the available actions for different items?
• How to define editable and non editable fields automatically?
• How to deal with thumbnails inside the table, or should the gallery view still be separate, and the table view replaces the list view?